StreamReader.ReadLine（）在不行时将行读为空

Question

我正在尝试从csv文件中读取数据：

    private static void ReadAnimalData(string file, Dictionary<string, Branch> branches)
    {
        string town = null;

        using (StreamReader reader = new StreamReader(@file))
        {
            string line = null;
            line = reader.ReadLine();
            if (line != null)
            {
                town = line;
            }
            Branch branch = branches[town];
            while (null != (line = reader.ReadLine()))
            {
                string[] values = line.Split(',');
                char type = Convert.ToChar(line[0]);
                string name = values[1];
                int chipId = int.Parse(values[2]);
                string breed = values[3];
                string owner = values[4];
                string phone = values[5];
                DateTime vd = DateTime.Parse(values[6]);
                Console.WriteLine(type);

                switch (type)
                {
                    case 'D':
                        bool aggressive = bool.Parse(values[7]);
                        Dog dog = new Dog(name, chipId, breed, owner, phone, vd, aggressive);
                        branch.Dogs.Add(dog);
                        break;
                    case 'C':
                        Cat cat = new Cat(name, chipId, breed, owner, phone, vd);
                        branch.Cats.Add(cat);
                        break;
                }
            }
        }
    }

数据文件：

Kaunas
D,Reksas,823,Buldogas,Jonas,867424992,2015-07-24,TRUE
C,Morkus,658,Siamo,Antanas,865412654,2014-11-24
D,Keksas,456,Taksas,Petras,866612345,2014-12-01,FALSE
...

但是，以下代码不起作用。它按预期读取第一行，但读取第二行会导致错误（IndexOutOfRangeExeption）。发生错误是因为某些原因reader.ReadLine()将该行读为""。可能是造成这个问题的原因是什么？